Electrical systems and communication cabling systems including emergency call taking systems including 911, E911, public-safety-access points (PSAPs), nurse/hospital equipment, and the like, require grounding of the equipment in order to satisfy safety standards (e.g., UL requirements, etc.) Electrical cabling communication systems that are required to be grounded must be connected to the earth. The grounding mechanism must provide a reliable means to safely conduct voltages which can be interrupted or rapidly affected by other sources such as lightning, line surges, unintentional contact with high voltage lines or equipment to ground, and the like. By effectively grounding telecommunication equipment, the equipment and the phone service can be protected, personal safety can be ensured when workers and others are exposed to the equipment, system performance can be ensured, and the like.
In emergency call taking equipment, there is also a requirement to detect and decode caller ID information from the phone line. Unlike non-emergency equipment which is completely floating and present a longitudinal balance to the telephone line, emergency equipment that is grounded can struggle to generate enough common mode rejection ratio. In some environments, the phone line may include common mode (e.g., 60 Hz common mode). In these situations, a portion of the 60 Hz harmonics, which can be up to or more than 4000 Hz, can be translated as differential mode signals that prevent the emergency call taking equipment from properly detecting caller ID information.